regextract ↗

Use the regextract() function to extract a substring from a field value using a regular expression pattern. The function returns the first captured group from the regex match. This is a scalar function used within the alter stage.

Syntax

| alter <output_field> = regextract(<field>, "<regex_pattern>")

Parameters

Name Type Required Description
field string Yes The string field from which to extract a substring.
regex_pattern string (regex) Yes A regular expression pattern with at least one capture group (). The function returns the content matched by the first capture group.

Returns

Type: string

Description: The regextract() function returns the substring matched by the first capture group in the regular expression. Returns NULL if the pattern does not match the input string or if the input field is NULL.

Usage notes

  • Capture groups: The regex pattern must contain at least one capture group defined by parentheses (). Only the first capture group is returned.
  • No match: If the regex does not match the input string, the function returns NULL.
  • Case sensitivity: Regular expression matching is case-sensitive by default.
  • Escape characters: Special regex characters must be escaped with a backslash \ (for example, \. to match a literal dot).
  • Scalar function: regextract() is a scalar function used in the alter stage, not an aggregation function. The function operates on each row individually.
  • Multiple extractions: To extract multiple parts from a string, use multiple alter statements with different capture groups.

Examples

Example 1: Extract domain from email address

Goal: Extract the domain portion from an email address field.

XQL code:

dataset = xdr_data
| alter domain = regextract(actor_effective_username, "@(.+)$")

Explanation: The regex @(.+)$ matches the @ symbol followed by one or more characters until the end of the string. The capture group (.+) captures the domain portion.

Output:

ACTOR_EFFECTIVE_USERNAME DOMAIN
admin@example.com example.com
user1@corp.local corp.local
svc_account@internal.net internal.net

Example 2: Extract IP address from a log message

Goal: Extract an IPv4 address from a free-text log message.

XQL code:

dataset = xdr_data
| alter extracted_ip = regextract(action_file_path, "(\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})")

Explanation: The regex pattern (\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}) matches an IPv4 address pattern. The entire match is captured by the outer parentheses.

Output:

ACTION_FILE_PATH EXTRACTED_IP
Connection from 192.168.1.100 on port 443 192.168.1.100
Failed login attempt from 10.0.0.5 10.0.0.5
No IP in this entry null

Example 3: Extract file extension from file path

Goal: Extract the file extension from a file path.

XQL code:

dataset = xdr_data
| alter file_ext = regextract(action_file_path, "\.([^.]+)$")

Explanation: The regex \.([^.]+)$ matches a literal dot followed by one or more non-dot characters at the end of the string. The capture group ([^.]+) captures the file extension without the dot.

Output:

ACTION_FILE_PATH FILE_EXT
C:\Windows\System32\cmd.exe exe
/var/log/syslog.log log
/tmp/archive.tar.gz gz